The present invention generally relates to integrated circuit devices such as the central processing units (CPUs) of computers. More particularly, the invention relates to the cooling of such integrated circuits for enhanced electronic performance.
It is well known in the electronics industry that cooling integrated circuit devices to below ambient temperature will substantially improve the efficiency and speed at which such devices can operate. Such cooling is particularly beneficial in microprocessors that form the CPU of modern day computers. For example, it has been found that the performance of a desktop computer can be significantly improved by cooling the CPU to temperatures of xe2x88x9240xc2x0 C. or below.
In the past, various techniques have been proposed for cooling CPUs and other integrated circuit devices to temperatures below ambient. For example, KryoTech, Inc., the assignee of the present invention, has previously developed a refrigeration system for cooling a CPU in a desktop computer. This refrigeration system operated by a circulating refrigerant fluid to a thermal head engaging the CPU.
The thermal head defined a flow channel through which the refrigerant fluid would pass as it circulated around the closed loop of the refrigeration system. Due to its design, the thermal head functioned as an evaporator where the refrigerant fluid was converted from liquid to gaseous form. In accordance with known thermodynamic principles, thermal energy was thus removed from the location of the CPU. The gaseous refrigerant, drawn from the evaporator by a compressor, was then fed back to a condenser where the thermal energy was removed.
As one skilled in the art will appreciate, the use of a refrigeration system in conjunction with electronic equipment raises a variety of issues. For example, undesirable condensation can develop on the computer""s motherboard unless appropriate preventative measures are taken. To provide a secure seal around the thermal head, the housing in which the thermal head is located has been permanently affixed to the motherboard itself. Such an arrangement, however, makes removal of the motherboard difficult after the refrigeration system has been installed in the computer. This permanent attachment may also require opening of the refrigeration system in order to repair or replace the motherboard.
According to one aspect, the present invention provides an apparatus for cooling an electronic device. The apparatus comprises a mounting structure having a receiving aperture in alignment with the electronic device. A thermal head is adapted to be inserted into and guided by the receiving aperture such that a cooled surface of the thermal head will be in thermal contact with the electronic device. The thermal head defines a flow channel for passage of a refrigerant fluid so as to cause cooling at the cooled surface. A clamping arrangement is attached to the mounting structure to maintain the thermal head in operative position. The apparatus further includes a refrigeration system in fluid communication with the flow channel of the thermal head to supply refrigerant fluid thereto.
In some exemplary embodiments, the mounting structure comprises a thermal housing having an interior in which the electronic device is located. The thermal housing serves to isolate the interior thereof from an ambient environment. Often, it will be desirable to form the thermal housing of thermally conductive metal, such as aluminum. This permits, for example, the provision of a heater element for heating an outer surface of the thermal housing so as to prevent condensation from forming thereon. Advantageously, the mounting structure may be fixed to a circuit board on which the electronic device is mounted.
Embodiments are contemplated in which the thermal head is axially movable in the receiving aperture of the mounting structure. In such embodiments, the clamping arrangement may include a spring element to urge the thermal head into engagement with the electronic device. The thermal head may further include a peripheral seal engaging an inner wall of the receiving aperture. In this regard, the receiving aperture and the thermal head may each advantageously have a generally cylindrical configuration.
In some exemplary embodiments, the thermal head will be removably secured by the clamping arrangement with respect to the mounting structure. The clamping arrangement may include a clamping flange movable with respect to the thermal head. The clamping flange in such embodiments may being fixed with respect to the mounting structure when attached thereto. Often, it will be desirable to further equip the clamping arrangement with a clamping collar movable with respect to the clamping flange and the thermal head. A spring element, located between the clamping collar and the thermal head, may also be provided to urge the thermal head into engagement with the electronic device.
Often, it will be desirable to make the inlet tube and outlet tubes through which refrigerant fluid flows to and from the thermal head sufficiently flexible to provide mechanical isolation to the thermal head. For example, the outlet tube may be a corrugated metal tube with the inlet tube being a capillary tube. In some exemplary embodiments, the flow channel of the thermal head has a configuration generally characterized by a plurality of arcuate and concentric passage segments.
Other aspects of the present invention are provided by a thermal housing for attachment to a planar circuit board having thereon at least one electronic device to be cooled. The thermal housing comprises a removable first housing member located on a first side of the circuit board. The first housing member defines an interior in which the electronic device is located. A removable second housing member is located on a second side of the circuit board opposite to the first housing member such that the circuit board will be sandwiched therebetween. At least the first housing member is formed of a thermally conductive material. Furthermore, a first heater element is associated with the first housing member to heat an outer surface thereof so as to prevent condensation from forming thereon. Preferably, the first housing member in such embodiments may define a first groove on its outer surface in which the first heater element is located.
Often, it will be desirable to also construct the second housing member of a thermally conductive material. In such embodiments, a second heater element may be associated with the second housing member. For example, the first and second housing members may each be formed of aluminum. First and second resilient seals may be respectively located between the first and second housing members and the circuit board.
Often, it may be desirable to configure the first housing member so as to have a block portion defining a receiving aperture in which a thermal head of a cooling apparatus is inserted. A wall portion of the first housing member will define a thin wall for engagement with the circuit board. Preferably, the thin wall of the first housing member will be configured to define a path around electronic components mounted to the circuit board. A desiccant material may be located in the interior of the first housing member to absorb moisture located therein.
Still further aspects of the present invention are achieved by an apparatus comprising a planar circuit board having thereon at least one electronic device to be cooled. A thermal housing having a removable first housing member and a removable second housing member is also provided. The first housing member is located on a first side of the circuit board and defines an interior in which the electronic device is located. The first housing member further defines a receiving aperture in alignment with the electronic device. A thermal head of the apparatus is adapted to be inserted into and guided by the receiving aperture such that a cooled surface of the thermal head will be in thermal contact with the electronic device. The second housing member is located on a second side of the circuit board opposite to the first housing member such that the circuit board will be sandwiched therebetween.
Additional aspects of the present invention are achieved by an evaporator for a cooling apparatus used for cooling an electronic device. The evaporator comprises a thermal head having a cooled surface for thermal contact with the electronic device. The thermal head defines a flow channel for passage of a refrigerant fluid so as to cause cooling at the cooled surface. The flow channel has a configuration generally characterized by a plurality of arcuate and concentric passage segments. The flow channel of the thermal head further has an inlet and outlet for respective ingress and egress of the refrigerant fluid. An inlet tube is provided in fluid communication with the inlet and an outlet tube is provided in fluid communication with the outlet.
In some preferred embodiments, the flow channel has scalloped sidewalls characteristic of the flow channel being formed by interconnected drill holes. Furthermore, the thermal head may comprise a first portion and a second portion made of disparate metals which are connected together to yield an integral structure. For example, the first portion of the thermal head may be formed of brass and the second portion of the thermal head may be formed of copper.
Other aspects of the present invention are provided by an apparatus for cooling an electronic device. The apparatus comprises a mounting structure having a receiving aperture in alignment with the electronic device. A thermal head is axially movable in the receiving aperture such that a cooled surface of the thermal head will be guided into thermal contact with the electronic device. The thermal head defines a flow channel for passage of a refrigerant fluid so as to cause cooling at the cooled surface. A clamping arrangement is attached to the mounting structure to maintain the thermal head in operative position. The clamping arrangement includes a spring element, such as a helical wave spring, to urge the thermal head into engagement with the electronic device.
Further aspects of the present invention are achieved by an evaporator for a cooling apparatus used for cooling an electronic device. The evaporator comprises a thermal head having a cooled surface for thermal contact with the electronic device. The thermal head defines a flow channel for passage of a refrigerant fluid so as to cause cooling at the cooled surface. The flow channel of the thermal head has an inlet and outlet for respective ingress and egress of the refrigerant fluid. An inlet tube and an outlet tube are provided in fluid communication with the inlet and outlet of the thermal head, respectively. The inlet tube is located inside of the outlet tube for a predetermined length so as to provide a counterflow heat exchanger. In exemplary embodiments, the predetermined length in which the two tubes are coaxial will be at least approximately one (1) foot.
Still further aspects of the present invention are achieved by apparatus for cooling an electronic device. The apparatus comprises a thermal housing having an interior in which the electronic device is located. The thermal housing serves to isolate the interior thereof from an ambient environment. A desiccant material is located in the interior of the thermal housing to absorb moisture located therein. A thermal head having a cooled surface in thermal contact with the electronic device is also provided. The thermal head defines a flow channel for passage of a refrigerant fluid so as to cause cooling at the cooled surface.
Other objects, features and aspects of the present invention are discussed in greater detail below.